Tuesday, September 30, 2008

The Circulatory System

The circulatory system is a blood distribution network which is responsible for transporting nutrients, water, and oxygen throughout the entire body to your billions of body cells, carrying away wastes such as carbon dioxide that body cells produce. As blood circulates through the body, oxygen and nutrients diffuse from the blood into cells surrounding the capillaries, and carbon dioxide diffuses into the blood from the capillary cells. From a point of view of its performance, the circulatory System is divided into three major parts: coronary circulation, pulmonary circulation, and systemic circulation.

Coronary circulation: Coronary circulation refers to the movement of blood through the tissues of the heart. The circulation of blood through the heart muscle is carried out by the coronary arteries and its branches. It is just one part of the overall circulatory system of the body. Serious heart damage may occur if the heart tissue does not receive a normal supply of oxygen-rich blood. This happens when a branch of the coronary arteries gets occluded (clogged). The heart tissue receives nourishment through the capillaries located in the heart.

Pulmonary circulation: Pulmonary circulation is the portion of the circulatory system which carries carbondioxide-containing blood away from the heart to the lungs, and returns oxygenated blood back to the heart. This is just one phase of the overall circulatory system. Oxygen-depleted blood enters the right atrium of the heart and flows into the right ventricle where it is pumped through the pulmonary arteries to the lungs. Pulmonary veins return the now oxygen-rich blood to the heart, where it enters the left atrium before flowing into the left ventricle. From the left ventricle the oxygen-rich blood is pumped out via the aorta on to the rest of the body.

Systemic circulation: Systemic circulation is the portion of the circulatory system that carries oxygenated blood away from the heart to the rest of the body, and returns carbondioxide-containing blood back to the heart. Arteries always take blood away from the heart, regardless of their oxygenation, and veins always bring blood back. In general, arteries bring oxygenated blood to the tissues; veins bring deoxygenated blood back to the heart. In the case of the pulmonary vessels, however, the oxygenation is reversed: the pulmonary artery takes deoxygenated blood from the heart to the lungs, and oxygenated blood is pumped back through the pulmonary vein to the heart.

From an anantomical point of view, the circulatory system is made up of the heart and blood vessels. Together, these provide a continuous flow of blood to your body, supplying the tissues with oxygen and nutrients. Arteries carry blood away from the heart; veins return blood to the heart.